Here are 13 facts to mark another Friday the 13th

13 is said to be unlucky for some and if you have Paraskevidekatriaphobia, which is a fear of Friday the 13th, this is definitely the case - but why does the number 13 evoke so much emotion in people?
To mark Friday the 13th and the sixth day of Science Foundation Ireland Science Week, Dr Richard J. Smith from the UCD School of Mathematics and Statistics has compiled a list of thirteen thrilling facts about the number thirteen.